American Oil and Gas Reporter - June 2023 - 42

FIGURE 1
Kuparuk Field Injector Well I-1 Conformance Treatment Summary
6,000
TOTAL INJ. RATE (BPD)
5,000
4,000
3,000
2,000
1,000
POLYMER CONC. (ppm)
WHP (psi)
5,000
10,000
15,000
20,000
12,000
10,000
8,000
6,000
4,000
2,000
25,000
When managing a casing leak, ultralow-molecular-weight
polymers, plus
cross-linkers are advantageous in treating
tight or pinhole casing leaks where cement
cannot penetrate or hold. After successfully
penetrating the offending area, the polymer
can be set up as a rigid ringing gel. This
process can eliminate the need for permanent
mechanical solutions (i.e., liners)
that can restrict production. In addition,
this process does not require drilling out,
making it considerably more cost-effective
for the operator.
When strong channeling communicaFIGURE
2
Decline in Injectivity After Conformance Treatment
12
10
8
6
4
2
Conformance
Treatment
tion exists from injection wells to producing
wells, waterflood performance can be
compromised-sometimes severely. Large
quantities of water may be cycled through
the formation, resulting in limited development
of an oil bank, limited contact
with oil-saturated rock, and high water
handling costs to produce a limited volume
of oil. The bulk gel is injected into the
formation, which blocks the strong channels,
forcing subsequent water injection
to move into tighter, oil-saturated rock.
Bulk gels are injected into the formations
as a gelant solution, a pre-gel
containing both polymer and cross-linker.
The gelant moves into the predominant
water flow path, which is the most permeable
zone (fractures or permeable
matrix rock). The gel forms after it is in
the formation. For practical purposes,
bulk gels provide a complete shutoff of
water flow in the zones in which they
are placed.
4
6
8
10
12
CUMULATIVE INJECTION (MM RB)
14
16
18
FIGURE 3
Incremental Oil Production from Four Offsets after Conformance Treatment
11,000
10,500
10,000
9,500
9,000
Unmodified data
IWR corrected plot
Trend line of baseline data
8,500
8,000
10
12
14
42 THE AMERICAN OIL & GAS REPORTER
16
18
TPV CUMULATIVE INJECTED (% TPV)
20
22
Oil production slows down due to lack of
MI gas injection in the pad, but picks up
again as MI injection is resumed.
Conformance
Treatment
Candidates for injection well bulk gel
treatments are patterns where rapid channels
or thief zones exist. An important consideration
is that a significant amount of bypassed
oil may be left in place that can be
easily recovered through a gel treatment.
The injection well must be able to accept
the gel, which has a substantially
higher viscosity than water. Another consideration
is that the operator should be
prepared to commit to a pattern for a
minimum of several months without making
changes after the gel treatment is
placed. This is very important to determine
incremental oil recovery through posttreatment
evaluation.
In a conformance gel treatment, the
goal is to fill the largest possible portion
of the conductive channels from the injection
well to one or more offset producers.
Several strategies can be used to
size gel treatments, and all of them fall
under the general categories of volume
or distance. A volume sizing strategy
refers to filling a portion of the channel
volume from the injector to the
producer(s). A distance strategy refers to
placing the gel at a specified distance
from the injection well.
OIL PROD CUMULATIVE (MSTB)
HALL INJECTION PRESSURE (Psi.Days x 106
)
INJECTION RATE (BP) & PRESSURE (psi)
POLYMER CONCENTRATION (ppm)
American Oil and Gas Reporter - June 2023

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